如果日期改变则执行操作

Question

如果日期改变,我需要执行一些操作.在应用程序启动时的意思是检查今天的日期,如果今天的日期是从最后24小时的时间改变,那么它将执行一些操作.是否可能因为我们不需要运行后台线程.我只想在委托方法中添加某种条件.

喜欢:如果在应用程序启动它首先保存今天日期并保存该日期.再次登录后,它会将该日期与当前日期进行比较,如果将其更改为24小时更改日期,则会执行某些操作.我怎么做的？xc

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions

Answer 1

在didFinishLaunchingWithOptions方法中添加以下代码行

//for new date change
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(timeChange) name:UIApplicationSignificantTimeChangeNotification object:nil];

在YourApplicationDelegate.m文件中实现方法

-(void)timeChange
{
  //Do necessary work here
}

编辑:混合@ZeMoon's答案,这将完美,所以timeChange方法的变化

-(void)timeChange
{
  if ([[NSUserDefaults standardUserDefaults] objectForKey:@"LastLoginTime"] != nil)
  {
    NSDate *lastDate = [[NSUserDefaults standardUserDefaults] objectForKey:@"LastLoginTime"];
    NSDate *currentDate = [NSDate date];

    NSTimeInterval distanceBetweenDates = [currentDate timeIntervalSinceDate:lastDate];
    double secondsInAnHour = 3600;
    NSInteger hoursBetweenDates = distanceBetweenDates / secondsInAnHour;

    if (hoursBetweenDates >= 24)
    {
        //Perform operation here.
    }
  }

  [[NSUserDefaults standardUserDefaults] setObject:[NSDate date] forKey:@"LastLoginTime"];//Store current date
}